The Design And Application Of Thermal Mass Flowmeter

In the production process of modern industry,in order to effectively carry out the production operation and control,the need to measure various physical parameters in the production process. Among them,flow is one of important parameters often measured and control needs.Usually,there are two methods of measuring volume and mass flow measurement. While the volume flow meter is often affected by the temperature, pressure and other conditions changes affect the accuracy of measurement.So, at the request of precise measurement occasion must use the mass flow measurement. Thermal mass flowmeter in this paper is the use of dissipation of heat(cooling) King’s law effect(King’s Law).Thermal Gas Mass Flowmeter(Thermal Mass Flowmeter),which based on the principle of convection heat transfer gas flow measurement, originated in the late 60 s.Measurement tools and compensation methods have been greatly improved with the development of microelctronics technology.The research direction of this project lies in the thermal gas mass flow meter design of a high precision, low velocity and large diameter is difficult to solve in the differential pressure flowmeter is widely used at present, this thermal gas mass flowmeter can realize. Using the heat dissipation effect of theKing’s Law,constant temperature difference testing method to achieve,it is based on a modular design concept, whole sealing, convenient installation and disassembly.According to the design requirements and the characteristics of subject, establish the design scheme of general and overall framework. Mainly in the following points:(1) The design of hardware systemIt’s mainly divided into three parts:sampling module,computing module and communication module.MSP430 MCU is used as the core of hardware design, adoptingmodular design concept.The sampling module is connected to measurement part,which changes measured flow into voltage signal and adjust it into input signal;The computing module compute the flow rate and accumulated flow,which are displayed on the LCD;The communication module is mainly responsible for the communication between TMF and PC.(2) The part of software designThe main part of software design for MCU, mainly realizes data acquisition, data processing, calculation and output function. And the same hardware part adopts modular design, to facilitate system maintenance and upgrades.(3) InstrumentationInstrument testing is to test the design to achieve the desired results. The subject finally the performance of the prototype is tested by experiment platform, the experimental results show the performance of thermal mass flowmeter in this project basically reached the expected requirements.